In this paper, we investigate the design of robust and secure transmission in intelligent reflecting surface (IRS) aided wireless communication systems. In particular, a multi-antenna access point (AP) communicates with a single-antenna legitimate receiver in the presence of multiple single-antenna eavesdroppers, where the artificial noise (AN) is transmitted to enhance the security performance. Besides, we assume that the cascaded AP-IRS-user channels are imperfect due to the channel estimation error. To minimize the transmit power, the beamforming vector at the transmitter, the AN covariance matrix, and the IRS phase shifts are jointly optimized subject to the outage rate probability constraints under the statistical cascaded channel state information (CSI) error model. To handle the resulting non-convex optimization problem, we first approximate the outage rate probability constraints by using the Bernstein-type inequality. Then, we develop a suboptimal algorithm based on alternating optimization, the penalty-based and semidefinite relaxation methods. Simulation results reveal that the proposed scheme significantly reduces the transmit power compared to other benchmark schemes.

中文翻译：

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不完美级联CSI智能反射地面辅助安全通信系统的鲁棒传输设计


在本文中，我们研究了智能反射面（IRS）辅助无线通信系统中稳健且安全的传输设计。特别是，多天线接入点（AP）在存在多个单天线窃听者的情况下与单天线合法接收器通信，其中传输人工噪声（AN）以增强安全性能。此外，我们假设由于信道估计误差，级联的 AP-IRS-用户信道是不完美的。为了最小化发射功率，发射机处的波束成形矢量、AN协方差矩阵和IRS相移在统计级联信道状态信息(CSI)误差模型下受到中断率概率约束的联合优化。为了处理由此产生的非凸优化问题，我们首先使用伯恩斯坦型不等式来近似停电概率约束。然后，我们开发了一种基于交替优化、基于惩罚和半定松弛方法的次优算法。仿真结果表明，与其他基准方案相比，所提出的方案显着降低了发射功率。